Journaling records redundant copies of database update information to increase protection against loss of information due to hardware and software failure. GT.M provides the M commands ZTSTART and ZTCOMMIT, to mark the beginning and end of a logical transaction. When ZTSTART and ZTCOMMIT fence a logical transaction, which may consist of multiple global variable updates, journal records can assure recovery of incomplete application transactions.
The following table summarizes the GT.M language extensions for journaling.
|
Journaling Extensions |
|
|
EXTENSION |
EXPLANATION |
|
View |
Extended to ensure that GT.M has transferred all updates to the journal file. |
|
ZTCommit |
Marks the completion of a logical transaction. |
|
ZTStart |
Marks the beginning of a logical transaction. |
|
$View() |
Extended for examining journaling status. |